1. Field of the Invention
The disclosure relates generally to devices designed to distract, or lengthen, bone sections separated by an osteotomy, in addition to serving as a permanent dental implant device. More particularly, the disclosure relates to distraction devices that are internally implantable in an upper or lower jaw, and that are capable of gradual adjustment to distract osteotomically separated bone sections for the purpose of enhancing bone growth. Devices disclosed herein also serve as permanent implants for purposes of restoring dentition.
2. Description of the Relevant Art
The use of dental implants for the replacement of teeth roots and restoration of dentition is known in the art. These devices are typically bullet shaped or screw shaped implants, or anchoring members, with an abutment (post) that extends through the gums and to which the replacement tooth or teeth are attached. The usual practice is to make an incision in the gum to expose the bone, drill a hole in the bone, place an implant in the hole, and then close the gum tissue. The implant is typically left in place for four to six months in order to allow osteointegration, after which the implant is uncovered and a post for rebuilding dentition is placed When there is a deficiency of bone, as occurs when a tooth has been missing for an extended time, for example, then a grafting procedure may be performed with the implant placement, or even four to six months prior to implant placement.
A variety of implant devices have been described. U.S. Pat. No. 4,682,951 to Linkow describes an implant device for use in an area of the maxilla adjacent a descendent portion of the maxillary sinus, particularly in patients with enlarged sinus cavities. This device is anchored in a hole that is predrilled through the bone and into the sinus cavity The anchoring device is a basket or cradle containing bone chips that is inserted into the area of the sinus cavity. The presence of this basket or cradle promotes new bone growth and the device becomes osteointegrated. Posts attached to this basket or cradle then serve as implants for the attachment of artificial teeth.
U.S. Pat. Nos. 4,744,753 and 4,886,456 to Ross and U.S. Pat. No. 4,906,191 to Soderberg describe devices and methods for forming dental prostheses. Prior to producing a model for use in tooth replacement, an implant is placed in the jaw and allowed to integrate. The replacement dentition is modeled, typically using a heat meltable material that forms around a post or screw attached to the implant. This model is then used in the manufacture of a permanent tooth or teeth.
U.S. Pat. Nos. 5,489,210 and 5,611,688 to Hanosh include expandable, bullet-shaped dental implants that are inserted into predrilled holes in the jaw and provide threaded connections for attachment of prostheses. These devices further provide internal threading for insertion of a screw within the device. Activation of this expander screw causes the implant to expand for more secure anchoring in the predrilled hole in the jaw. A dental implant device described in U.S. Pat. No. 5,725,377 includes an internal battery so that a small electrical field generated by the implant stimulates bone growth.
Bone distraction devices are also known in the art. Orthopedic distraction, for example, has been used for several decades. One method of promoting bone growth involves cutting the bone, distracting (separating) the two pieces of the bone a desired distance, setting the two ends in place by means of a bridge across the two bone sections, and filling the gap between the bone ends with a bone segment or graft.
Devices for gradual bone distraction are described in U.S. Pat. No. 4,096,857 to Kramer and U.S. Pat. No. 3,976,060 to Hildebrand. European Patent Application No. EP 0 791 337 to Razdolsky and Driscoll describes a device for lengthening the jaw by stretching the jaw of a young person during growth, a process that can be accomplished without cutting the jaw bone. The device is also described as useful in older patients and more severe cases when used in conjunction with a corticotomy. Several devices that may be attached externally to the jaw have been described for mandibular distraction. Examples of such devices include those described in European Patent Application No. EP 0 832 613, PCT Publication No. WO 98/09577 and U.S. Pat. No. 5,364,396.
There is still a need, however, for devices and methods that allow a practitioner to replace degenerated or otherwise deficient bone, and also to place a permanent implant device to be used for replacement dentition, without requiring separate surgeries for bone replacement and implant placement.